OK, let's do this. We've got 107 and 418 and we're adding them all together.

Step 1: We'll start by adding the digits 7 & 8 in column 1 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 0 & 1 in column 2 and get 2.

Step 3: We'll start by adding the digits 1 & 4 in column 3 and get 5.

So, 107 + 418 = 525.

